What are Bung, Diacetyl, and Winy: Brewing Terminology Tuesday
February 24, 2015
Bung The bung is the stopper for a keg or casket. The bung is placed in the hole that is used for filling up or emptying the keg, and the bung is usually placed in the keg during carbonation. Fun fact: the bung used in a cask for "real" beer, or ale, must be a wooden bung in order to allow the pressure during fermentation and carbonation to be released. Diacetyl Normally referred to as the buttery or butterscotch flavor found in homebrew. Diacetyl is a volatile compound that formulates in early fermentation, but begins to decrease as beers mature. There is a lot of science behind diacetyl and its formation, and understanding that science can help brewers better control it. According to the geniuses over at BYO, "While yeast cells synthesize certain key amino acids — such as valine, leucine and isoleucine — various intermediates are created in excess. In the case of diacetyl, the precursor is alpha acetolactate, which is excreted from the cell as the requirement for valine and leucine diminishes. Once outside the cell, alpha acetolactate can be oxidized to diacetyl." The thing to know is happy, healthy yeast will reabsorb diacetyl. This means that conditioning and maturing your beer with some yeast leftover will greatly increase your odds of removing that buttery smell and flavor from your homebrew. Also keep in mind that fermenting at warmer temperatures increases diacetyl production in your beer. So the best things to do to avoid diacetyl is to pitch healthy, happy yeasts, ferment at proper temperatures, and make sure you condition at proper temperatures to allow leftover yeasts to reabsorb any diacetyl that was created during fermentation. Winy This is exactly what it sounds like: a wine/ sherry type flavor in your homebrew. You might be thinking, "I love wine! What's wrong with this?" However, winy flavors usually result from the oxidation of your beer, and the other flavors that accompany that winy flavor are cardboard and paper. Yummy. Oxidation happens when your beer is exposed to oxygen, which degrades your beers flavors and aromas. Now, this isn't to say that anytime your beer comes in contact with oxygen during the brewing process, you're going to be drinking cardboard and wine later, it simply means that once your yeast is pitched in your fermenter and it has been sealed, you want to avoid oxygen contact at all costs. Same things goes for bottling time: it is best to do so "quietly," meaning you want to avoid any splashing, dumping, or all around agitation of your beer. Simply bottle, seal and leave it alone. This minimizes the amount of oxygen being introduced to your beer, and lowering your chances of oxidization. Our Brewmaster, Josh, will be discussing the oxidization of beer when bottling during this week's Livestream bottling and carbonating demonstration. The Livestream will be held Thursday, February 26th, from 6:00 - 7:00 pm MST. To learn more, make sure you join us using the button below! Plus, we might have a special coupon for those that join us live... guess you will have to tune in to find out! Check out our bottling livestream by clicking here.